I have LuaLaTeX installed via MiKTeX 2.9 on Windows 7. I am trying to use fontspec to change my document to a different font than the default CMR fonts. Just invoking \usepackage{fontspec} is sufficient to cause the following cryptic error message:

! This is a LaTeX bug: check coding!
! Command name `\font_set:Nnn' already defined! Current meaning:
!   \protected\long macro:#1#2#3->\tex_font:D #1=#2 at #3\scan_stop:
! See the LaTeX3 documentation for further information.
! For immediate help type H .

l.602 \cs_new:Npn \font_set:Nnn
                                #1#2#3 {

Continuing by hitting return produces a second similar message, and then processing apparently finishes without further fuss or bother.

Is there something I can do about this?

Or do I just have to wait until MiKTeX picks up the next release of LuaLaTex?

  • The underlying issue is the same as the one discussed in the question @Sharpie has pointed to. I'd therefore suggest it's a duplicate.
    – Joseph Wright
    Commented Apr 27, 2011 at 6:21
  • @Joseph, from the description and answers there, I'd say you are right. My only excuse is that I focused on LuaLaTex and ignored XeTex when searching for the problem before posting.
    – RBerteig
    Commented Apr 27, 2011 at 9:33

1 Answer 1


I ran into this bug a couple of weeks ago and I think the problem is not with LuaLaTeX, but with the fontspec package. Try upgrading that package.

See this question concerning the same error message, but produced by XeLaTeX:

xelatex compilation error

  • Letting MiKTeX's updater have its way with my install updated about 30 packages including fontspec. I can now compile without errors.
    – RBerteig
    Commented Apr 27, 2011 at 10:10

Not the answer you're looking for? Browse other questions tagged .